Non-perfusion severity correlates with central macular thickness and microvascular impairment in branch retinal vein occlusions

Purpose To study peripheral capillary non-perfusion (PCN-P) in branch retinal vein occlusion (BRVO) by means of ultra wide-field fluorescein angiography (UWFFA), and to correlate its extent and severity with optical coherence tomography (OCT) and OCT-angiography (OCTA) parameters and best corrected visual acuity (BCVA). Methods Prospective case series with 2 years of planned follow-up. We recruited patients from June 2019 to December 2019. Ophthalmologic examination included BCVA, UWFFA, OCT and OCTA. Partial (p) and complete (c) ischemic index (ISI) were evaluated on UWFFA images. Vessel density (VD) in both the macular region and the optic nerve head (ONH) was calculated. Results Twelve BRVO subjects and 12 healthy controls were recruited. Mean age was 63.8 +/- 8.74 years. Mean BCVA improved from 0.43 +/- 0.25 logMAR to 0.15 +/- 0.18 after two years (p < 0.01), while mean central macular thickness (CMT) decreased from 463.83 +/- 200.85 mu m to 353.17 +/- 108.85 mu m (p > 0.05). Mean cISI, pISI and total ISI were 25.2 +/- 13.0%, 6.3 +/- 5.0% and 31.5 +/- 12.0%, respectively. Except for VDs of the superficial capillary plexus and choriocapillaris in the macular region, all VDs were lower in the BRVO group (p < 0.01). cISI and tISI negatively correlated with mDCP (p < 0.01), whereas only pISI correlated with CMT at baseline (p < 0.05). Additionally, cISI also negatively correlated with VD at the ONH (p < 0.05). Conclusion The amount of complete and partial ischemia may have different implications in BRVO, with the former being more associated with microvascular impairment and the latter with macular edema.